import turtle

point=[0,0]
index = 1
step = -5
def up_goto(pos):
    turtle.up()
    turtle.goto(pos)
    turtle.down()


def move():
    turtle.clear()
    up_goto(point)
    turtle.dot(30, 'red')
    point[index] += step
    turtle.ontimer(move, 100)


def func_up():
    global index, step
    index = 1
    step = 5

def func_down():
    global index, step
    index = 1
    step = -5

def func_left():
    global index, step
    index = 0
    step = -5

def func_right():
    global index, step
    index = 0
    step = 5

turtle.tracer(False)
move()
turtle.onkeypress(func_up, 'Up')
turtle.onkeypress(func_down, 'Down')
turtle.onkeypress(func_left, 'Left')
turtle.onkeypress(func_right, 'Right')
turtle.listen()
turtle.done()